A Population-Based Validation of the IGCCCG Update Consortium for Survival in Metastatic Non-Seminoma Testis Cancer.

Background: In 2021, the International Germ Cell Cancer Collaborative Group (IGCCCG) Update Consortium reported improved overall survival (OS) rates in a modern cohort of metastatic non-seminoma testis cancer patients within each of the IGCCCG prognosis groups (96% in good vs. 89% in intermediate vs. 67% in poor), compared to the previous IGCCCG publication (92% in good vs. 80% in intermediate vs. 48% in poor). We hypothesized that a similar survival improvement may apply to a contemporary North-American population-based cohort of non-seminoma testis cancer patients. Patients and Methods: The Surveillance, Epidemiology, and End Results (SEER) database (2010-2018) was used. Kaplan-Meier plots and multivariable Cox regression models tested the effect of IGCCCG prognosis groups on overall mortality (OM). Results: Of 1672 surgically treated metastatic non-seminoma patients, 778 (47%) exhibited good vs. 251 (15%) intermediate vs. 643 (38%) poor prognosis. In the overall cohort, five-year OS rate was 94% for good prognosis vs. 87% for intermediate prognosis vs. 65% for poor prognosis. In multivariable Cox regression models predicting OM, intermediate (Hazard ratio [HR] 2.4, 95% confidence interval [CI] 1.4-3.9, P < 0.001) and poor prognosis group (HR 6.6, 95% CI 1.0-1.0, P < 0.001) were independent predictors of higher OM, relative to good prognosis group. Conclusions: The survival improvement reported by the IGCCCG Update Consortium is also operational in non-seminoma testis cancer patients within the most contemporary SEER database. This observation indicates that the survival improvement is not only applicable to centres of excellence, but also applies to other institutions at large.